The present invention relates in general to data traffic networks and, in particular, to a configuration of splitters, switches and data link selection devices within a data network to accomplish switching from a working data link to a protection data link and/or protection channel following the detection of a failure or fault in the network.
The use of public data networks as data transport mechanisms has proliferated and become common place. For example, network topologies using the Internet Protocol (IP) are now widely used as a means of communicating digital data and voice signals over long distances. An example of an IP-based network is the Internet or World Wide Web.
Typically, data traffic within a data network is transmitted from one location to another utilizing a series of routers, servers, gateways and other devices that are adapted to receive and transmit the data traffic over a series of data links or signaling channels. The routers or routing elements, in particular, utilize a routing algorithm in connection with a routing table to store possible destinations, the distance to such destinations and the route path used to reach them in order to direct data traffic within the network. A plurality of communications links made up of copper pair wiring, fiber optic cabling, or other transmission medium provide the signaling pathways that connect the routers. The distance between the routers is usually measured in xe2x80x9chopsxe2x80x9d or xe2x80x9cnodes,xe2x80x9d which refer to the number of routers that the data traffic encounters along a particular path. This distance can also be measured in other meaningful quantities.
The routers periodically communicate routing information among themselves propagating updated routing data which can be stored in the routing tables and utilized by the routing algorithms of the network. Each router and its routing table can by dynamically updated to indicate the shortest distance between nodes of the network. In this way, a router can examine the IP packets to be transmitted and, using the routing table, make a routing decision based on information regarding the distance between hop destinations and the overall load of the network. Other network topologies such as ATM switches, for example, use other forms of data routing schemes and other types of signaling protocols.
In general, the capacity of the network is defined by the number of data traffic links available for transmission of data traffic as well as the bandwidth of such links between any two nodes in the network. The bandwidth of the link can be defined in terms of the number of transmitted bids of traffic data per second, such as 1, 10, or 100 Mbits/s. Typically, a network is divided into an array of subnetworks which are associated with specified regions defining the network service area. The concentration of routers and other networking devices can be great in regions where network use is heavy or large amounts of data traffic is flowing. At the very minimum, a specified subregion of the network will include at least two routers or nodes designated as primary data traffic agents for incoming and outgoing data traffic within the subregion.
A factor that can significantly affect the performance of the network and overall network efficiency is the failure of the components and/or the data transmission links used to carry the data traffic. Such failures can be caused by a variety of factors, including cut lines, repairs, severe weather, and upgrades to the network, among others. In optical networks that offer higher transmission speeds (10 Gbit/s, for example) the failure of an optical link can lead to enormous loss of data.
While in most instances, a router is provided with the ability to redirect data traffic along an alternative data link once the primary or working data link has suffered a failure, the fastest possible recovery and reversion to the working data link is desired after detection of the failures. Additionally, while the data traffic can be redirected to ensure receipt at its intended destination node, the use of such alternative paths can increase congestion and decrease overall network performance. With the growing demands for increased speeds and improved data trafficking services, the ability to quickly restore primary transmission links after equipment failure is at a premium.
As such, it would be advantageous to provide an efficient way to overcome the effects of failures within the network and provide fast restoration of transmission links once a failure has been detected.
The present invention provides a configuration of line splitting and line selection devices that are adapted to provide fast and accurate recovery from equipment failures, such as failures in the primary optical working data link, the line terminating equipment and data routing devices. In the event a failure occurs over the working data link, the flow of data traffic in the network is maintained along a protection data link or a protection channel, as is appropriate. Link protection can be unidirectional or bidirectional to provide a protection mechanism both in the receive and transmit signaling channels. A protection data link and protection channel are provided and utilized to route data traffic in the event the working data link or a router""s working data port suffers a failure. Once the failure is repaired, data traffic flow is restored along the working data link or using the working data port to ensure the most efficient use of network resources.
According to one embodiment of the invention, disclosed is a network architecture providing link protection between nodes in a data traffic network. The data traffic network comprises a working data link as a communications pathway between first and second nodes of the network. The network also includes first and second routing elements that are predisposed and configured about the nodes and adapted to communicate data traffic over the working data link. A line or signal splitter is interspersed between the first routing element and the working data link about the first node.
The network also includes a link selector interspersed between the second routing element and the working data link about the second node. A protection data link forms a signal pathway between the signal splitter and the link selector with the signal splitter and link selector configured to switch the flow of data traffic from the working data link to the protection data link following the detection of a failure.
A short reach transmitter and short reach receiver are used and configured to provide communications between the first routing element and the signal splitter. The signal splitter and link selector are predisposed at the first and second nodes, respectively, and communicable coupled to each other through the working data link or protection data link, as determined by the failure status of the working data link. A long reach transmitter and a long reach receiver are used to communicate signals over the working data link or protection data link, as is appropriate.
In one embodiment, the link selector includes an optical line monitor configured to determine the transmission qualities of the working data link and the protection data link. The primary advantage of the monitor is its use to determine when to revert to the working data link after recovery from a failure.
Also disclosed is a network architecture suitable for use in a data traffic network that includes a plurality of nodes and a plurality of data links coupling the nodes. The network architecture includes a working data link that forms a signal pathway between an origination node and a designation node within the network. A protection data link is likewise provided and forms a second signal pathway between the same two nodes. A pair of routers are provided and predisposed about the nodes, respectively, and configured to provide for the transmission and reception of data traffic with the network. In one embodiment, the routers include both working and protection data ports with each set of ports including associated transmit and receive terminals. The routers also include short reach transmitters and receivers for transmitting and receiving data traffic via the data ports.
A line splitting device and a line selection device are used and configured to communicate with the first router using short reach transmitters and receivers. Likewise, a second line splitting device and second line selection device communicate with the second router via short reach transmitters and receivers. The network architecture also includes long reach transmitters and receivers for communicating data traffic over the working and protection data links. The network architecture provides data link protection following the detection of a failure by causing the first and second line splitting devices and the first and second line selection devices to switch between the working and protection data ports or between the working and protection data links, resulting in an almost uninterrupted signal path between the origination and designation nodes of the network.
In one embodiment, the first and second line selection devices each comprise a two-by-two (2xc3x972) switch with inputs coupled to the working and protection data links. In addition, each switch has a first output coupled to the first and second long reach receivers. A link monitor is provided and coupled to a second output terminal of the switch. The link monitor is configured to determine the transmission qualities of both the working and protection data links and is used in determining when the working data link has recovered from a failure.
The network architecture can also include a protection channel and a set of switching arrays coupled to either the protection ports or the working ports of the first and second routers. In this way, the switching arrays can be used to provide an alternative signal pathway for data traffic over the protection channel and from the protection or working ports of the routers. A configuration of short reach and long reach transmitters and receivers are utilized to direct traffic from the protection ports of the routers over the protection channel in the event the short reach or long reach transmission equipment or the associated switches or splitters experience a failure. The first and second switching arrays are preferably configured as a dual switch configuration for handling bidirectional data traffic in both the receive and transmit directions. The switching arrays can be configured in a 1:N arrangement providing localized link protection for a group of routers, or their corresponding ports, against failures in the optical terminating equipment, with N representing the number of ports in the group.
Also disclosed is a method of providing link protection in the event of a failure within a data traffic network consisting of a plurality of routers and a plurality of data links coupling the routers. The method includes the steps of detecting when a failure occurs over a working data link utilized by at least two routers in the network and then switching the flow of data traffic from said working data link to a protection data link until the recovery from the failure has been achieved. A configuration of splitting and link selection devices are used to revert the flow of data traffic from the protection data link to the working data link. The restoration step can be performed by monitoring the working data link to determine when it has recovered from the failure. The method can also include the step of providing a protection channel for carrying data traffic from a group of routers in a first geographic location to a second group of routers in a second geographic location in the event of a failure. The detection, switching and restoration steps can be performed in both the transmit and receive directions providing bidirectional link, switch, splitter, and router protection.
Variations of the above referenced network, network architecture and method are discussed in the following detailed description.
A technical advantage of the present invention is the achievement of link protection with existing routing equipment to provide localized link protection against failures in line components such as amplifiers and regenerators, for example.
Another technical advantage of the present invention is that the selection of a protection data link is automatic once a failure occurs on the working data link with automatic reversion to the working data link once a recovery from the failure has been detected.